Reversing flow valve

ABSTRACT

Valve structure for reversing gas flow comprising a housing containing a pair of disposed cylinder chambers, a pair of disposed manifold chambers, inlet and outlet means provided in each pair of said cylinder and manifold chambers, piston means provided in each cylinder chamber positioned therein to selectively effect flow between inlet means in said manifold chamber and outlet means in said cylinder chamber and flow between inlet means in said cylinder chamber and outlet means in said manifold chamber, said pistons slideably arranged in said cylinder chambers and fixedly mounted on piston rods, said rods extending slideably through the walls of the manifold chamber, and driving means connected to said piston rods for inducing said rods to reciprocate thereby effecting sliding motion of the pistons within said cylinder chambers and thereby reverse the flow between the inlet and outlet means in said cylinder chambers.

United States Patent 1 i 3,897,800 Tyrner et al. Aug. 5, 1975 REVERSINGFLOW VALVE [75] lnventors: Joseph M. Tyrner, Brookside: f ii g g ff G IP William 5 Watson Mt Tuhon both Amara Again m um rnest u erard v of NJ.

[73] Assignee: Allied Chemical Corporation, New [57] ABSTRACT York, NY.

Valve structure for reversing gas flow comprising a Filedi y 1973housing containing a pair of disposed cylinder cham [2H App NO; 378,749hers, a pair of disposed manifold chambers inlet and outlet meansprovided in each pair of said cylinder Related Application Data andmanifold chambers piston means provided in [60] Division of Ser. No.218.605. Jan. 17. 1972. Pat. No. each cylinder chamber positionedtherein to selec- 7 hi is a Continuation of tively effect flow betweeninlet means in said manifold 1969' ibundonedchamber andoutlet means insaid cylinder chamber and flow between inlet means in said cylinderchaml52l Cl l37/309i l37/625'43 her and outlet means in said manifoldchamber said [5]] F161 11/07 pistons slideably arranged in said cylinderchambers [58] Field of Search ]37/625'67- and fixedly mounted on pistonrods. said rods extendl37/625-43\ 310 ing slideably through the walls ofthe manifold chamher and driving means connected to said piston rods[56] References Cited for inducing said rods to reciprocate therebyeffecting UNITED STATES PATENTS sliding motion of the pistons withinsaid cylinder 65:.334 6/1900 Baker et all 137/6256) Chambers and therebyrcvcrse the between the 625L076 8/1901 Porter r v a 4 a l37/o25.69 inletand outlet means in said cylinder chambers. 1292.013 l/l9l9 Mungen,137/62567 I 3,739.8ll 6/!973 Gross 137/6353? 4 5 Drawmg F'gures I02 i iHi. /04 202 E r07 PATENTED AUG 51975 FIGJ PATENTED AUG 975 SHEET LEI a 2FIG? PATENTEU RUB 51975 SHEET PATENTED AUG 51975 T 897', 800

sum 4 FIG. 5

REVERSING FLOW VALVE This is a division of application Ser. No. 2l8.605.filed Jan, I7. 1972. now U.S. Pat. No. 3,773,066 which, in turn, is acontinuation of application Ser. No. 877,720, filed Nov. I8, 1969. nowabandoned.

This invention relates to a novel valve structure, and is directed moreparticularly to a four-way valve which may be used to rapidly reverseand redirect the flow of gas. It is particularly adapted for controllingand directing large volumes of gaseous reactants and product streams,whether hot or cold, to and from regenerative reactors or furnaces.

In the past it has been the practice to use reversing valves of varioustypes for such applications. In some types, separate valve seats andclosures, therefore, are provided for the inlet and outlet ports. inanother type. a single valve seat has an inlet and outlet port therein.adapted to be closed alternately by a door sliding on a seat. Thereversing valves of the prior art are generally not suitable forscale-up to large sizes. They operate too slowly for those applicationswherein a rapid switch in direction of the gas streams is essential, andwherein appreciable mixing of the gas streams during the reversingoperation must be avoided.

It is the object of this invention to provide a reversing valve havingthe capability of reversing and redirecting gas flows very rapidly andcompletely, and one capable of scale-up for large flow, high volumeoperations, without loss of its fast acting characteristics, and itsability to avoid mixing of gas streams.

These and other objects are accomplished according to our invention by avalve structure having a housing comprising a pair of cylinder chambershaving reciprocating pistons therein and a pair of manifold chamberscommunicating with said cylinder chambers. Each of the pair of cylinderand manifold chambers has an inlet port and an outlet port. Thearrangement of these two pairs of chambers is such, that gas enteringthe inlet port of the manifold chamber will flow through the outlet portof the cylinder chamber and gas entering the inlet port in the cylinderchamber will leave the outlet port of the manifold chamber. The pistonsare so positioned that upon reciprocation the functions of the inlet andoutlet ports of the cylinder chambers are reversed.

The pistons, which may be fitted with piston rings, are slideablyarranged within the cylinders, and affixed to piston rods. These rods,which may consist of hollow shafting, slideably pass through seals inthe manifold shells at those points at which they would normally impingeon the manifold shell when extended.

Driving means are provided for inducing a reciprocating motion to thepiston assemblies, whereby the sliding motion of the pistons alternatelycarry them to points in the cylinder chambers beyond the cylinder portsin either direction. The piston rods are structurally connected in amanner such that as one piston slides in the direction of the outletmanifold, the other piston slides oppositely, i.e., toward the inletmanifold.

An important feature of the valve is that the cylinder ports comprise asmall fraction of the total distance which the piston travels in thecylinder chamber, so that in operation the piston passes across thecylinder ports at maximum velocity thereby making the switch quickly andcleanly, avoiding intermingling of the reaction and product gases asthey pass through the valve.

Also. by passing a gas or vapor under positive pressure through hollowpiston rods and suitable passageways to the channel between the pistonrings at the periphery of the piston, a seal is produced between thepiston and cylinder chamber wall which prevents mixing of the gasstreams by movement past the pistons. These same hollow piston rods andpassageways may also serve as the means of introducing high temperatureand corrosion resistant lubricants. such as molybdenum sulfide, to thesliding surfaces of the piston and cylinder wall to facilitate movement.

The invention and the objects and advantages thereof may be appreciatedfrom consideration of the following description taken in connection withthe accompanying drawings, in which:

FIG. 1 is a schematic representation of a system in which the valve ofthe present invention may be employed;

FIG. 2 is a longitudinal vertical section of one embodiment of thereversing valve of the present invention;

FIG. 3 is a cross sectional view of the valve of FIG. 2, taken alongline A,A.

FIG. 4 is a longitudinal vertical section of a structural variation ofthe reversing valve of the present invention;

FIG. 5 is a longitudinal vertical section of a portion of the pistonassembly of the valve structure of the present invention showing thesealing feature.

In the schematic diagram shown in FIG. I, a reaction gas enters thesystem via line 2 and passes to flow reversing valve 6, via line 4. Inthe embodiment shown the reaction gases leave valve 6 via line 8 to heatex change chamber 10 wherein the reaction gases are heated to thedesired temperature by any of the well known heat exchange means, e.g.,heat exchange tubes, packed refractory column, etc. The reaction gasesleave chamber 10 via line 12 and enter reaction chamber 14 wherein thereaction takes place. The product gases exit chamber 14 via line 16 andpass down through heat exchange chamber 18 wherein the product gases arecooled to a desired temperature. The cooled product gases leave chamber18 and pass to valve 6 via line 20. The product gases pass through valve6 and leave the system via line 22.

During the above cycle valves 24 and 26 are open and valves 28 and 30are closed. Once the cycle is reversed, which may take place from everyfew seconds up to about every hour, reversing flow valve, 6, switchesand valves 24 and 26 are closed and valves 28 and 30 are opened. Thereaction gases now pass through flow valve 6 to chamber 18 via line 20(dotted) to reaction chamber 14 via line 34. The product gases leavereactor 14 and pass via line 36 to exchange chamber 10 to valve 6 vialine 8 and leave the system via line 22.

Now referring to FIGS. 2, 3, and 4, the valve comprises a housing, 6,with an inlet manifold connecting with cylinder chambers 102 and 103 atpoints I04 and 105, respectively. The manifold inlet is shown as 106.Similarly, outlet manifold I07 is connected to cylinder chambers 102 and103 at points 108 and 109, respectively. and is provided with an outletat 110. Inlet manifold port 106 is connected to line 4 (FIG. I) andoutlet manifold port 110 is connected to line 22 (FIG. 1).

The cylinder ports III and [12 may consist of either a single transverseslot (not shown) or a multiplicity of openings centrally grouped in thecylinder wall. In FIGS. 3 and 4 they are shown as longitudinal slotsrepresenting the preferred embodiment. A jacket 113 and 114, surroundsthe cylinder ports having openings I15 and I16 which convey gas eitherto or from the cylin der ports via lines 8 and 20, respectively (FIG.1).

The piston assemblies comprise pistons 117 and 118 fixed by mounting topiston rods I19 and 120, respectively, which are slideably positionedconcentric to cylinder chambers I02 and 103 and extend slideably throughthe walls of the manifolds at seals I21 and 122.

While the driving means are represented as hydraulie, and shown as 123in FIG. 2, other modes of driving the pistons in a reciprocating mannermay be employed. In FIGS. 2 and 3, a structural connection between thepiston rods 119 and 120 is shown as 124, so arranged that when onepiston slides in the direction of one of the manifolds, the other slidesaway from it. A manner of connecting the piston rods to thereciprocating driving means, using cables or chain and pulleys orsprockets, is shown in FIG. 2 as 125. The structural connection chosento maintain this relationship between the two pistons may take manyforms. Since the pistons are parallel, and spaced apart. the connectionas shown in FIG. 2 is a system of cables or chains and pulleys orsprockets. In FIG. 4, the connection is represented merely by acontinuation of the piston rods, joining them as one. since the pistonsin this configura tion of the valve are aligned.

FIG. 5 illustrates a method of sealing the pistons against the cylinderchamber walls to prevent by-pass and intermingling of the process gases,by supplying a sealing gas or vapor to the periphery of the pistons.Where the gases being valved are hot, the sealant may be steam. In thisvariation, piston rod 119 is hollow. Sealing gas under pressure can beconveyed into this hollow shaft or shafts by flexible connections notshown. Passageway 20] conveys the sealing gas from hollow piston rod 119to an encircling channel 202 in the periphery of piston 117. This sameroute may be used for the introduction of high temperature corrosionresistant lubricants. A sectional view ofa portion of this pistonassemblage shows piston 117, piston rings 205 and cylinder chamber Wall206.

The operation of the reversing flow valve of the present invention willbe better understood by reference to the above described drawings. InFIGS. 2 and 4, with pistons I17 and 118 in the positions shown, gasentering valve 6 by manifold inlet 106 via line 4 (FIG. I) iseffectively blocked from passage to cylinder chamber 102 by piston 117.Since piston 118 is on the far side of port II2, with respect to theentering gas, the gas leaves the cylinder 103, enters jacket 114,leaving through its opening 116.

In the system as shown in FIG. 1, gas leaving valve 6 would be directedthrough conduit 8 to heat exchange chamber 10 and would return to thevalve as described above, entering from conduit into opening 115 (FIGS 2and 4). It enters cylinder chamber 102 through port 111. Its passage toinlet manifold I00 and cylinder chamber 103 is blocked by pistons 117and 118, respectively, and passes to manifold chamber I07 and leaves bymanifold outlet 110 and exits from the system via line 22 (FIG. I). Asthe processing condi tions require, the reciprocating driving means 123will cause the pistons to start moving in a reciprocating fashion, reachmaximum speed near the mid-point of ports Ill and 112, then decelerateto zero at the end of their strokes at positions 126 and 127,respectively.

Important to this invention is the fact that the distance travelled bythe pistons over their respective ports, represents a small fraction ofthe total distance travelled, and this distance is essentially at thepoint of maximum velocity of the piston. The switching operation,therefore, takes place in a small fraction of it time its takes thepistons to travel from one end of their respective cylinders to theother.

With the pistons at the opposite ends of the cylinders (not shown) theincoming gas entering at inlet 106 can no longer reach cylinder chamberport 112 since it is now blocked by piston 118, which has moved uptoward inlet manifold chamber to position 127 (FIG. 4). The gas enterscylinder chamber 102 and leaves the valve by port 111 which is now inflow communication with inlet manifold chamber 100 by movement of piston117 towards the outlet manifold chamber 107, to position 126 (FIG. 4).It now can be seen that gas en tering inlet 106, which on the previouscycle left via outlet 116, now leaves via outlet 115. Opening 106 isalways an inlet, and opening 110 an outlet, but the direction of flow atopenings and 116 has been reversed.

We claim:

1. A valve structure comprising:

a. first and second manifold chambers;

b. first and second cylinder chambers;

c. an inlet port provided in the first manifold chamber;

d. an outlet port provided in the second manifold chamber;

e. a first port provided in the first cylinder chamber;

f. a second port provided in the second cylinder chamber;

g. a piston provided in each of the first and second cylinder chambers,each piston having a first position therein which permits communicationbetween said inlet port of said first manifold chamber and said firstport of said first cylinder chamber and communication between saidsecond port of said second cylinder chamber and said outlet port of saidsecond manifold chamber;

h. said pistons being slideably arranged in said first and secondcylinder chambers for movement over the first and second ports thereofand being fixedly mounted on a single piston rod;

i. drive means connected to said piston rod for inducing said rod toreciprocate, thereby effecting sliding motion of the pistons within saidfirst and second cylinder chambers and causing movement of the pistonsto a second position in said cylinder chamber which terminatescommunication be tween said inlet port of said first manifold chamberand said first port of said first cylinder chamber and communicationbetween said second port of said second cylinder chamber and said outletport of said second manifold chamber and which provides communicationbetween said inlet port of said first manifold chamber and said secondport of said second cylinder chamber and between said first port of saidfirst cylinder chamber and said outlet port of said second manifoldchamber;

j. said pistons having sealing surfaces and said first and second portsand said sealing surfaces having widths extending in the direction ofmovement of said pistons the width of each of the sealing surfaces beingless than that of the port over which it moves and the shortest distancebetween the sealing surfaces being greater than that between the firstand second cylinder chamber ports. whereby said pistons and first andsecond ports of said first and second cylinder chambers provideuninterrupted communication between said inlet port of said firstmanifold chamber and said first and second ports of said first andsecond cylinder chambers. and uninterrupted communication between saidfirst and second ports of said first and second cylinder chambers andsaid outlet port of said second manifold chamber during said movement ofthe pistons to the second position, said pistons moving over the firstand second ports for a distance which represents a small fraction of thetotal distance traveled by the pistons during said movement to thesecond position.

2. The valve structure of claim 1, wherein said first and secondcylinder chambers are in alignment with a manifold chamber between them.

3. The valve structure of claim 1, wherein the drive means compriseshydraulic means.

4. The valve structure ofclaim 1, wherein the periphery of the pistonsand the interior surface of said first and second cylinder chambersthrough which the pistons slide are in sealed relationship.

t t i t

1. A valve structure comprising: a. first and second manifold chambers;b. first and second cylinder chambers; c. an inlet port provided in thefirst manifold chamber; d. an outlet port provided in the secondmanifold chamber; e. a first port provided in the first cylinderchamber; f. a second port provided in the second cylinder chamber; g. apiston provided in each of the first and second cylinder chambers, eachpiston having a first position therein which permits communicationbetween said inlet port of said first manifold chamber and said firstport of said first cylinder chamber and communication between saidsecond port of said second cylinder chamber and said outlet port of saidsecond manifold chamber; h. said pistons being slideably arranged insaid first and second cylinder chambers for movement over the first andsecond ports thereof and being fixedly mounted on a single piston rod;i. drive means connected to said piston rod for inducing said rod toreciprocate, thereby effecting sliding motion of the pistons within saidfirst and second cylinder chambers and causing movement of the pistonsto a second position in said cylinder chamber which terminatescommunication between said inlet port of said first manifold chamber andsaid first port of said first cylinder chamber and communication betweensaid second port of said second cylinder chamber and said outlet port ofsaid second manifold chamber and which provides communication betweensaid inlet port of said first manifold chamber and said second port ofsaid second cylinder chamber and between said first port of said firstcylinder chamber and said outlet port of said second manifold chamber;j. said pistons having sealing surfaces and said first and second portsand said sealing surfaces having widths extending in the direction ofmovement of said pistons, the width of each of the sealing surfacesbeing less than that of the port over which it moves and the shortestdistance between the sealing surfaces being greater than that betweenthe first and second cylinder chamber ports, whereby said pistons andfirst and second ports of said first and second cylinder chambersprovide uninterrupted communication between said inlet port of saidfirst manifold chamber and said first and second ports of said first andsecond cylinder chambers, and uninterrupted communication between saidfirst and second ports of said first and second cylinder chambers andsaid outlet port of said second manifold chamber during said movement ofthe pistons to the second position, said pistons moving over the firstand second ports for a distance which represents a small fraction of thetotal distance traveled by the pistons during said movement to thesecond position.
 2. The valve structure of claim 1, wherein said firstand second cylinder chambers are in alignment with a manifold chamberbetween them.
 3. The valve structure of claim 1, wherein the drive meanscomprises hydraulic means.
 4. The valve structure of claim 1, whereinthe periphery of the pistons and the interior surface of said first andsecond cylinder chambers through which the pistons slide are in sealedrelationship.